When television systems were simple and programming sources were few, families accepted the limitation of only being able to view a single program at a time. Simple television systems advanced to become entertainment systems with integrated stereo sound and more sophisticated video reception and display capabilities. Picture in a picture (PIP) television made it possible for families to view multiple programs at the same time on a single monitor. Thus one member could watch a sporting event transmitted via cable television while the other members watched a videotaped movie. As computers are integrated into the entertainment system the multiprogramming possibilities are greatly increased. The oversized monitors of today can support simultaneous presentation of multiple video programs.
For each of the viewing options, however, the audio options are limited. Where the entertainment system is comprised of multiple programming sources, the audio output from all of the sources can be directed through a stereo amplifier. This provides centralized control, but it limits the viewers to hearing only one program at a time, regardless how many programs are being viewed. Where multiple programs are viewed on the same monitor, the audio portion of only one program is presented at a time, and those viewing the other programs must do without sound. If multiple monitors are used, each may have its own speaker system and project the audio for the program being viewed, but this creates a cacophony of sound which is unlistenable when different family members watch different programs in the same room. One solution for those families who wish to view multiple programs at the same time is to construct multiple entertainment systems. As the devices get more complex, however, they get more expensive, and the duplication of components places multiple systems out of the economic reach of most people. When the entertainment system presents programming which is available in multiplexed format (whether it be via picture in a picture television technology, multi-window computer presentations, or a combination of the two), duplication of components does not address the function of multi-window display. Video display technology has kept pace with the need for simultaneously presenting different video programs to different viewers. There has not been a comparable advance in audio presentation technology.
The restriction to single channel audio output is unworkable when the programming sources are primarily entertainment-oriented. A family cannot use all of the functions of a sophisticated multi-channel video presentation when they are limited to hearing the audio output of only one program at a time. If only one of the programs being viewed has sound, there is little value in viewing the programs for which sound is not projected. The restriction to a single audio output becomes more significant when the home entertainment system is expanded to provide information as well as entertainment by incorporating a computer. The computer is employed both as a programming source as well as an intelligent controller for the entertainment and information system. In a home entertainment and information system, signals generated by the various programming sources can be multiplexed by the computer. The signals for a television program and a computer-based multimedia application may be multiplexed and transmitted to a single monitor and simultaneously displayed, each program in its own window on the monitor.
Software running on the computer has a sound aspect as well as a visual aspect. It may be as simple as a warning beep, or as sophisticated as a multimedia presentation containing CD-quality sound. In either event, like television programming, without the sound aspect the usefulness of the program to the user is reduced. One partial solution to the problem of simultaneously transmitting audio signals from multiple sources (such as a CD player or AM/FM tuner) is a multiple zone audio system, described in U.S. Pat. No. 5,182,552 to Paynting. That system consists of a centralized group of audio programming sources, connected to an array of speakers and controlled by multiple remote control devices. Each remote control device controls which audio source's signals will be transmitted on the channel associated with the remote control device. This allows independent access of the different program signals in different zones. The problem of simultaneously transmitting independent audio programming to the same zone remains. There is a need to provide multiple simultaneous users of an entertainment system with the audio portion of the different programs being viewed whether they are in the same or different rooms.